another victim of the new shy generation of men that doesn't understand social nudity among the guys! DUDE- there are basically 3 different types of guys in the locker room:
1 100% straight guys (one in a thousand who are really 100!) who aren't interested in your body, but who know what a spontaneous erection is and that it's not controllable sometimes
2 100% gay guys (few are totally 100!) who are going to look (and maybe smile) when they see your semi. They may even start to get wood themselves- are you gonna be uptight if that happens? You know how a boner sometimes can be a domino effect among young guys.
3 Guys who are somewhere in the middle, and who will appreciate seeing a healthy guy with a working libido and a bouncing trouser snake. Whenever I am at the club, I am always an attraction to guys my own age- that's the social dynamic of like-persons hanging together.
My point is, every guy looks. Some look to be "alpha dog" and compare. Some look because they want some. Some look because you're in a frakkin' locker room and you can't look any direction without seeing a bare ass or crotch weasel. The locker room was made to be naked in.
The only way you will become relaxed to being naked around the guys is to DO IT. Sure, at first you might get stiff. What's really WRONG with that when you think about it? It's part of being a guy. Guys aren't gonna judge you- they're gonna think you're healthy. Some guys have to jump thru alot of hoops to get anything growing down there- and other guys have more of a 'hair trigger'. Dude it's OK in any way!
Maybe one guy in 100 would think something was amuk and that you were being inappropriate. Only one in 500 would actually say something about it. With those odds, man- don't sweat it- toss the towel over the shoulder and let it go where it goes.
I'm serious, man. At my health club every weeknight I see probably 150-200 guys naked, in all shapes and levels of hard. Rarely is a cock past straight out from the body- but sometimes that's an issue of how long the guy is soft- and if it rides on a big set of balls it can point straight out and look like wood. That's normal too, and guys know this.
Even if you get a FULL ON, rock hard, hard bone... (worst case scenario) again, all guys know that it can happen occasionally with no warning. Some will look, and smile. A buddy might bust your balls about it ("happy to see me?") but no damage done. Just counter with the old standby ("yeah it has a mind of its own") or ("too much viagra this morning") and that's all that is necessary as you slip your boxers on and you've done yourself proud.
All guys like hard cock, man- even the 100% straight guys. Ever heard of a guy that likes porn but wants the guy to have a stubby pencil dick? HELL NO! If you get worked up, be normal about it, and let it do it's thing until you get some clothes on it. Once you actually DO THIS for a week or two, you'll resolve your nervous tension about being naked among the guys and you won't get hard anymore in those situations.
(By the way man I'm on the opposite side of the fence: I usually stay pretty flaccid after a hard workout and when I get cold in the shower i get shrinkage, so I feel like I am shortchanged!)

So enjoy the attention, and don't worry about perceived negative attention. After all no matter how much we think about ourselves being naked, everyone else is naked too and not everyone in the room is thinking about it!
Best of luck to you.